Electronically programmable servo-controlled power feed and spindle drive system for an automatic screw machine

Abstract

A retrofit for an electronically programmable, servo-controlled power feed and spindle drive system for controlling the spindle and cam shaft drive of an automatic screw machine. The automatic screw machine originally provides rotational power to the spindles of the cam shaft drive through a complex series of gears, shafts and clutch systems. The gears, shafts and clutch systems also provide synchronization between the rotation of the spindles and the rotation of the cam shaft drive. A retrofit of the automatic screw machine includes replacement of the complex series of gears, shafts and clutch systems with a variable speed drive motor, a chain drive system, an electronic encoder for monitoring the rotational speed of the spindle shaft, an electric servo motor for providing rotational power to the cam shaft drive and a central processing unit to synchronize the speeds of the variable speed motor and electric servo motor. The result is an automatic screw machine adapted with an electronic control system that requires minimum alteration or reconstruction of the original machine.

What is claimed is: 
     
       1. An apparatus for providing rotational power to a set of sipindles and to a cam drive system of a multiple spindle automatic screw machine, the apparatus comprising: a variable speed drive motor and a separate servo motor;   a central processing unit connected to the variable speed motor and to the servo motor for independently controlling the speed of each motor;   a main shaft receiving rotational power from the drive motor trough a first continuous power loop and having a speed of rotation that is a function of the speed of the variable speed motor;   a spindle shaft providing rotational power to the spindles, the servo motor being drivably connected to the cam drive system; and   a second continuous power loop communicating power from the main shaft to the spindle shaft;   the second continuous loop being a chain drive system having a first sprocket attached to the main shaft, a second sprocket attached to the spindle shaft and a chain in mechanical communication between the first sprocket and the second sprocket such that the speed of rotation of the main shaft relative to the spindle shaft remains constant.   
     
     
       2. An apparatus for electronically controlling a set of rotatable spindles and a cam drive system of an automatic screw machine whereby the spindles have a controlled speed of rotation, the apparatus comprising: a variable speed drive motor and a separate servo motor, the servo motor being drivably connected to the cam drive system;   a main shaft receiving rotational power from the drive motor through a first continuous power loop and having a speed of rotation that is a function of the speed of the variable speed motor;   a spindle shaft providing rotational power to the set of spindles;   a second continuous power loop communicating power from the main shaft to the spindle shaft;   a central processing unit;   an encoder converting mechanical rotational motion into an electronic signal, the encoder monitoring the rotation speed of the spindle shaft;   a first electrical transmission line providing electronic communication between the variable speed drive motor and the central processing unit;   a second electrical transmission line providing electronic data communication between the encoder and the central processing unit;   a third electrical transmission line between the servo motor and the central processing unit; and   the central procssing unit optimizing the rotation of the spindle shaft by monitoring the rotational speed of the spindle shaft and controlling separately the speed of the variable speed drive motor and the servo motor;   the second continuous power loop being a chain drive system having a first sprocket attached to the main shaft, a second sprocket attached to the spindle shaft and a chain in mechanical communication between the first sprocket and the second sprocket such that the speed of rotation of the spindle shaft relative to the speed of rotation of the main shaft remains constant.   
     
     
       3. The apparatus of claim 2 wherein the encoder is located in the automatic screw machine and is mechanically coupled to the main shaft. 
     
     
       4. An apparatus for electronically controlling a spindle and a cam drive system of an automatic screw machine whereby the spindle has a controlled speed of rotation, the apparatus comprising: a variable speed drive motor and a servo motor;   a main shaft receiving rotational power from the drive motor through a continuous power loop whereby it is driven at a controlled speed of rotation;   a spindle shaft providing rotational power to the spindle;   the servo motor being drivably connected to the cam drive system:   a chain drive system communicating power from the main shaft to the spindle shaft, the chain drive system having a first sprocket attached to the main shaft, a second sprocket attached to the spindle shaft and a chain providing mechanical communication therebetween such that the speed of rotation of the spindle shaft relative to the speed of rotation of the main shaft remains constant;   a central processing unit;   an encoder relating mechanical rotational motion into an electronic signal, the encoder located on the interior of the automatic screw machine and mechanically coupled to the main shaft;   a first electrical transmission line providing electronic communication between the variable speed drive motor and the central processing unit;   a second electrical transmission line providing electronic data communication between the encoder and the central processing unit;   a third electrical transmission line between the servo motor and the central processing unit;   whereby the central processing unit receives data from the encoder and monitors the rotational speed of the main shaft, the speed of the variable speed motor and the speed of the servo motor thereby being controlled by the central processing unit to effect predetermined speeds of the spindle shaft and the servo motor.   
     
     
       5. An apparatus for electronically controlling a rotating spindle and an automatic screw machine having a tool feed, the apparatus comprising: a variable speed drive motor for developing rotational power;   a main shaft receiving rotational power from the drive motor through a continuous power loop and driven at a controlled speed of rotation;   a spindle shaft providing rotational power to a set of spindles, the spindle shaft having a controlled speed of rotation;   a chain drive system communicating power from the main shaft to the spindle shaft, the chain drive system having a first sprocket attached to the motor shaft, a second sprocket attached to the spindle shaft and a chain providing mechanical communication therebetween such that the speed of rotation of the spindle shaft relative to the speed of rotation of the main shaft remains constant;   a central processing unit;   an encoder converting mechanical rotational motion into an electronic signal; the encoder being located in the interior of the automatic screw machine and mechanically coupled to the mainshaft;   an electric servo motor for developing rotational power;   a worm gear assembly;   a coupling between the electric servo motor and the worm gear assembly;   a worm shaft assembly driven by the worm gear assembly, the worm gear assembly being used to transfer the rotational power of the servo motor 90° to the worm shaft assembly;   a drum shaft driven by the worm shaft assembly;   a drum driven by the drum shaft;   a set of tool slides indexed by the drum;   a first electrical transmission line providing electronic communication between the variable speed drive motor and the central processing unit;   a second electrical transmission line providing electronic data communication between the encoder and the central processing unit;   a third electrical transmission line providing electronic communication between the electric servo motor and the central processing unit;   whereby the central processing unit receives data from the encoder and monitors the rotational speed of the main shaft the speed of the variable speed motor thereby being controlled by the central processing unit to effect predetermined speeds of the spindle shaft;   the central processing unit independently controlling the operation of the electric servo motor and synchronizing the operation of the set of tool slides with the rotational speed of the spindle shaft.   
     
     
       6. A retrofit for an automatic screw machine originally having a drive motor connected with a continuous power loop to a main shaft that is connected to a spindle shaft through a multi-speed gear set, a secondary shaft and a gear train, the secondary shaft being connected to a set of tool slides through a set of beveled gears, a clutch system, a large worm gear set, a drum shaft and a drum, the clutch system being connected to the spindle shaft by a small worm gear set, the drive motor, multi-speed gear set, secondary shaft, gear train, beveled gears, clutch system, large worm gear set and small worm gear set being replaced by: a variable speed drive motor;   a first continuous power loop communicating power from the variable speed drive motor to the main shaft;   a second continuous power loop communicating power from the main shaft to the spindle shaft;   the spindle shaft and the main shaft each having a controlled speed of rotation;   an encoder converting mechanical rotational motion into an electronic signal, the encoder being located on the interior of the automatic screw machine and being mechanically coupled to an end of the main shaft;   electric servo motor;   a worm gear assembly;   a coupling between the electric servo motor and the worm gear assembly;   a worm shaft, assembly driven by the worm gear assembly, the worm gear assembly being used to transfer the rotational power of the servo motor 90° degrees to the worm shaft assembly;   a central processing unit;   a first electrical transmission line providing electronic communication between the variable speed drive motor and the central processing unit;   a second electrical transmission line providing electronic data communication between the encoder and the central processing unit; and   a third electrical transmission line providing electronic communication between the electric servo motor and the central processing unit;   whereby the central processing unit receives data from the encoder and monitors the rotational speed of the main shaft, the speed of the variable speed motor and the speed of the servo motor thereby being controlled by the central processing unit to effect predetermined speeds of the spindle shaft;   the central processing unit independently controlling the operation of the electric servo motor and synchronizing the operation of the set of tool slides with the rotational speed of the spindle shaft;   the second continuous loop being a chain drive system having a first sprocket attached to the main shaft, a second sprocket attached to the spindle shaft and a chain in mechanical communication between the first sprocket and the second sprocket such that the speed of rotation of the spindle shaft relative to the speed of rotation of the main shaft remains constant.   
     
     
       7. A retrofit for an automatic screw machine originally having a drive motor connected with a continuous power loop to a main shaft that is connected to a spindle shaft through a multi-speed gear set, a secondary shaft and a gear train, the shaft being further connected to a set of tool slides through a set of beveled gears, a clutch system, a large worm gear set, a drum shaft and a drum, the clutch system being connected to the spindle shaft by a small worm gear set, the drive motor, multi-speed gear set, secondary shaft, gear train, beveled gears, clutch system, large worm gear set and small worm gear set being replaced by: a variable speed drive motor;   a first continuous power loop communicating power from the variable speed drive motor to the main shaft;   the spindle shaft and the main shaft each having a controlled speed of rotation;   a chain drive system having a first sprocket attached to the main shaft, a second sprocket attached to the spindle shaft and a chain in mechanical communication between the first sprocket and the second sprocket such that the speed of rotation of the second sprocket relative to the speed of rotation of the first sprocket remains constant;   a second continuous power loop communicating power from the main shaft to the spindle shaft;   an encoder converting mechanical rotational motion into an electronic signal, the encoder being located on the interior of the automatic screw machine and being mechanically coupled to an end of the main shaft;   an electric servo motor;   a worm gear assembly;   a coupling between the electric servo motor and the worm gear assembly;   a worm shaft assembly driven by the worm gear assembly, the worm gear assembly being used to transfer rotational power of the servo motor 90° degrees to the worm gear assembly;   a central processing unit;   a first electrical transmission line providing electronic communication between the variable speed drive motor and the central processing unit;   a second electrical transmission line providing electronic data communication between the encoder and the central processing unit;   a third electrical transmission line providing electronic data communication between the electric servo motor and the central processing unit;   whereby the central processing unit receives data from the encoder and monitors the rotational speed of the main shaft the speed of the variable speed motor and the speed of the servo motor thereby being controlled by the central processing unit to effect predetermined speeds of the spindle shaft;   the central processing unit independently controlling the operation of the electric servo motor and synchronizing the operation of the set of tool slides with the rotational speed of the spindle shaft.